What do YOU want? Are you just dating to have some fun or are you looking for a serious relationship? If the latter, going with someone significantly older might be a bad idea. It really narrows down your options.
A lot of women approaching 40 start to freak out about getting older and not being sexually attractive to every man they meet. Some people see this as a relief and some see it as a death sentence. I have both kinds of friends. The ones that don't choose to age gracefully can make the most terrible asses of themselves chasing younger men.
I'm not saying that the 38 year old was only interested in you for an ego boost, but it's a distinct possibility but I'd hate to see you waste your time on someone who doesn't want you for you.
Age is "just a number" if you believe that, but to some people, it's an obsession. It ain't pretty, either.