Is my hamster pregnant????? please help!!

[dawnhill]

Hi i am a new owner of 2 adorable "male" chinese dwarf hamsters which i bought on 26th april.
I left them for a few days and last night i stroked them both and gave them attention for about 5 mins, they are both very friendly but 1 is ALOT more nervous than the other.
I came downstairs this morning to find that the more nervous had made a nest and dragged alot of sawdust, tissue paper and bedding into the pipe on the front of the cage "he" comes out occasionally to eat a bit of food and runs around the cage frantically other than that just stays in the tunnel all the time?
Could this be because i scared him by stroking them or could "he" be "she" thats pregnant???
i dont know if i should pick it up to check the sex or just leave it and see what happens??
Please help im new to this so unsure what i should do

Many thanks for reading xx