I don't know how old you are but I just turned 40 last month.
Before I remarried (my husband is actually 10 years older than me) I had the same thing. I don't think I would call it a problem per say, but it is an interesting phenomenon that has been going on for years now according to my single girl friends.
I personally think it is because as a man grows older, the immaturity and instability of a lot of 20 something women just isn't what they are looking for. They don't want to be a surrogate father, they want maturity and independence. Women my age are usually established, financially independent and know what they are looking for out of life. I think that younger men find those traits attractive.
As far as men your age feeling intimidated by you, that's a real possibility. When a woman is all of those things I described above, men can feel like you really don't need them for anything and men need to be needed. (My husband told me that when we were dating.) If they don't feel needed then insecurity sets in and that's when they feel intimidated. It's an odd balance that my husband and I had to reach before we got married so we both felt secure in the relationship.
At least that's my two cents. :)