That sounds like a weird off-hand complaint until you realize that she's not talking about once or twice -- she's talking about "making it a point" to do so. Even once or twice is perilous territory, unless it's in a particular context (she brings up the subject in conversation, for instance).
That is, he was attracted to her, and wanted to let her know it. This comes up a lot when people believe that anything said with "positive intent" to women is actually positive. A lot of geeks don't get this. Women aren't stupid -- they recognize the compliment for what it is. Whenever you feel like you need to say something to a woman because your genitals throb -- think better of it.
I've made this mistake -- it was subtle, not egregious (like the guy above), but I did. Nothing happened, and maybe she never noticed, but in retrospect, it's one of the those embarrassing things you do in life you get to re-live in idle moments. Don't let this happen to you. :-)
It's important to understand that sexuality comes up everywhere. In our work cultures, we generally try to suppress it because even in an office with all men, it can become a distraction.
With women in the workspace, it's much worse. Our society trains us to think of women as sexual objects who must always prioritize a man's perspective. Even if you are "enlightened", it's easy to slip up if you're too casual about it. When you want to offer a compliment on someone's appearance (in a nominally non-sexual context), you need to understand where it is coming from -- and do not lie to yourself. It's okay to be sexually attracted to someone in the workplace (that's humanity), but not ok to impose your desires on someone else without their consent.