First of all congratulations on your return to the fold!!! I've always maintained that once you become a trumpeter you'll always be a trumpeter.
40 years young eh? I don't see any reason why you shouldn't make any real progress on the trumpet, providing of course that you put in a bit of the right sort of practice. I'm glad you've been brave enough to start again from scratch as this will allow the embouchure muscles to develop gradually. The only problems I foresee are boredom and frustration , both having quite simple solutions!!!!!
Let's face it, it can be a bit tedious honking away on your own in a practice room and I think I'm not alone in my feelings!!!!! I think it's really important to join a brass band/big band/wind band or any other form of music group that you might find interesting. When I look back at my progress as a kid, there is no doubt in my mind that I progessed much quicker as a direct result of the amount of banding, competitions and chamber music I was involved in. This gave me exposure to different styles of music (relieves the boredom factor!) and with all the competitons I went in for, gave me realistic goals to practice for. It's always good to compare your progress against other people's in these situations too. If you're too busy to do any of this you could always try some of the play along CD's that are around, where you can have anything from a jazz trio to a full size symphony orchestra as your accompaniment.
When it comes to frustration, like I've already mentioned, if you set yourself some realistic goals you shouldn't have any problems. Just don't expect to get to Wynton Marsalis' standard after a couple of years of 30 mins a day practice!!
Good Luck with it all and please stay in touch!