For months we’ve been hearing from our local bankers that “some people” are overleveraged in their commercial real estate portfolios – not them, of course, and not anyone they would name, but definitely someone.

As the nation claws its way out of the last recession, pessimists – or as we like to call ourselves, realists – are looking ahead to where the next pothole lies. (Hopefully it’s not a crater that knocks all the wheels off the bus like the last one; hopefully it’s just a frost heave. Our economic engine can take a dent, but not another crash.)

CRE is a real concern, particularly in Boston, where towers seem to sprout like mushrooms overnight. To be sure, thousands of people move to the metro area every year and they all have to live and work somewhere – those towers are not standing vacant.

But the economy is a funny and fragile thing. While our so-called “knowledge economy” isn’t going anywhere – it’s not like Harvard and MIT are going to up stakes and move to Connecticut – the effect it is having on the lives of everyday citizens can’t be discounted. As Scott Van Voorhis covers in his column this week, economist Richard Florida contends that the downtown tech boom is destroying the middle and working class.

Again, again, again we say: we do not have enough housing stock. Something must be done. But it’s already too late. We have surpassed the record median home prices set a mere 12 years ago and are headed up, up, up.

It is unsustainable and it is dangerous. Low- and no-down payment loans are making a comeback. Ability to Repay may help keep some of that in check, but it hardly matters. We learn from our past mistakes (and legislate the crap out of the industries that made them) but there will always be more unscrupulous businessmen and businesswomen looking to make a buck on the backs of the middle and working class.

Which brings us back to CRE. People need to live somewhere and the suburban cities and towns are loath to allow multifamily housing of any type. Just look at Belmont, which fought for over a decade to keep out a 40B project of not even market rate housing, but luxury.

And now luxury is all there is. It’s too expensive to build anything else in the commonwealth. So yes, likely there are banks and lenders overleveraged in their portfolios and approving loans that would not have been even a few years ago. There’s money to be made, and people will make it.

But the sky not yet falling. As Steve Adams reports this week, analysis of the overall market finds it in quite good shape, with credit standards tightening again. That’s good news for now, but that pothole still exists. As the economy improves, the optimism returns, the money flows – and mistakes are made. Without care and caution, the wheels will most assuredly fall off the bus.