transmission problem

I had my chevy 2000 venture manifold gasket and crankshaft oil seal changed yesterday. but when i drove it home i noticed it took a little longer and high rev before it shifts to the next gear. I need your help. thank you very much!!

is overdrive off? any check engine light

Thanks FishFind, but seems like problem is solved. i will still have to keep an eye on it for a couple of days. I found some of the vacuum and some electrical connections not properly plugged-in. just hope that this is really the reason behind it.