The Angry Planes and No Clip script mods for GTA 5 were secretly harboring some truly nasty malware. Uninstall them ASAP if you already grabbed the offending mods, and check this forum thread for how to remove their keylogger cargo.
You should definitely change your passwords, too: if you typed them in at any point after activating Angry Planes or No Clip, there's no telling who may have them by now. Both mods have been pulled down from gta5-mods.com, though Angry Planes creator "onsby" was still posting in its comments section as recently as yesterday.
Aside from the obvious privacy concerns, it's doubly disheartening that a bizarrely humorous mod like Angry Planes (which packs the skies over San Andreas with military jets, stunt planes, and airliners, all single-mindedly trying to kill you) was apparently a Trojan horse this whole time.
Its lighthearted appeal fooled us, too - we apologize for including Angry Planes in our GTA 5 PC mod round-up. As much fun as it is to drop weird new stuff from the internet into a well-established game, this is a sad reminder that you always have to be vigilant about who and what you trust with your computer.