Totally normal. The color discharge most women have (because we always have some kind of discharge going on, even when we're healthy) is anything from clear to whitish to yellowish. And of course brownish before or after a period.

Mine tends to be a whitish to yellowish, so of course all my panties got stained. I haven't started investing in pantyliners yet because I haven't had the money to buy new undies. When I do, though, I'll keep the old for period days and the new I'll just wear with pantyliners.

So yes, totally normal and an unfortunate aspect to having a vagina.