My undiagnosed OCD may have reached its zenith

I was walking from the T to work this morning, and saw one of those convertable PT Cruisers parked in the South End that had a giant Spongebob sticker in the back window. As this is not something you see in that neighborhood too often, I looked closer, and saw that the car had a licence plate frame that read "I'm a Boston University Alumni". Now, my Latin may be a bit rusty, but unless I'm mistaken, "alumni" is the masculine plural form, with "alumnus" being the masculine singular. Now, had the frame simply read "Boston University Alumni", I'd be fine with it- it would have just meant that the owner of the car is among the alumni. That, however, is not what it said. I couldn't stop thinking about it as I walked away, and actually found myself checking my manpurse/messenger bag for a pen, so I could leave a note on this person's windshield, politely informing them of their Latin grammatical error. That's when it occured to me that I may obsessing too much. I can assure you, though- it's not actual OCD. On a completely unrelated note, you'll have to excuse me now, as I have to go flip the light switch exactly 17 times and count the threads in my office carpet.