Recently, I changed my air filter. Ever since then my transmission has been shift oddly.

It seems that when the trans shifts from 2nd to 3rd gear it hangs for a bit. It gets a bit better when warm, but still the same. Their are no clunks and the trans fluid is topped off with no fluid leaks. It is not slipping, but hanging from when it initially starts shifting to completely being in third gear. Could this be a vacuum issue??