Should I email my professor about a recommendation letter if he has offered me a job? So I've just finished my Master's and my advisor has offered me a tentative position to work in his lab. I say tentative because it's dependent on if his project gets funding. He emailed me recently right before his leave that his project has been shortlisted and that they'll hopefully hear back by early Fall and that he'll keep me updated with regards to the position. This was last month and in the meantime i've been doing an internship to keep busy. 

Recently however I've been thinking about applying to other jobs and PhD positions to keep my options open. However, I'm not sure if it's appropriate to ask my advisor if I can list him down as one of my reference and I don't want to blow my chances with him either. I drafted an email telling him that as his offer is not yet guaranteed I'm considering applying to various other positions and if he would be able to provide me a letter of recommendation. Yet I made it clear that I would still prefer to work with him. Is this fine? Or should I not ask him at all as he might then see me as a fickle candidate?
As you seem to have a good relationship with that professor, I think it is wise to ask for his recommendation. In some context, the absence of a recommendation from the former advisor could be frown upon.

I think any normal researcher will understand why you are applying to other positions, especially if you mention that his offer is your number 1 choice. In short, yes, ask!