I was washing my tap water filter which had a couple of brown stains when some water drops fell on my nostrils, am i at risk from naegleria fowleri?

No: In real life, there is no increased risk of catching Naegleria when that happens under normal circumstances in the U.S.

Extraordinarily tiny: risk. Naegleria fowleri is most often found in warm lakes, rivers, hot springs, warm water discharged from industrial plans,& poorly chlorinated or un-chlorinated pools. “Naegleria fowleri can grow in public & private water tanks and pipes, especially where little or no disinfectant (like chlorine or chloramine) is present. It can also grow in the pipes & water heaters of homes & buildings.“ REF