Yes, it is possibly an air leak. Could be either the Intake Manifold Gasket issue or it could be a leak around the EGR. The first thing I would do is make sure the EGR bolts are tight.

I had a similar experience when I opened up the EGR for the cleaning and didn't tighten the bolts enough when I put it back together. And don't overtighten because if you break a bolt there, it will be a pain to extract.