masquerading as astigmatism?

Hi, can a fast reflector that is not thermally equilibrated (i.e. brought from a warm room to a cold outside) give rise to what appears as astigmatism? I'm familiar with the shimmering images due to tube currents, but here I see elongated ovals inside and outside of focus point, and these elongated ovals are orthogonal to each other- almost textbook astigmatism. I just got the scope, so I need to test it out a few more nights. Just wondering if one of the optical experts here had an opinion. Thanks, Ivan

Ivan:

A few specifics might be a help. GSO Dobs used to have issues with pinched secondaries...

Jon