Weird resonance

Hi guys. This isn't really a problem, but it's an observation about my guitarlele and I was wondering how common it is. When I play a high A (open A string or 5th fret on the E string) the sound seems to go on forever. After a bit of fiddling, I figured out that it's because it causes the wound strings to vibrate, and if I damp them, then it doesn't happen. It would make sense to me if it was causing the low A string to resonate, but it's doing the same thing on the D string. Is this common?

D and A are in each other's harmonic frequencies, so sounds pretty expected to me.

Typically, if the notes are a perfect 5th apart, they will resonate with each other. I actually use a Snark tuner for 98% of the way, and then tune the last fraction by listening to the 1 and 2 strings vibrating together, and then the 3 and 4 strings together, since those sets are (typically) tuned a perfect 5th apart. When you're perfectly in tune, you can literally hear the sine waves of each frequency syncing up together. Super cool and fun!

Thanks. I was wondering if it was something like that

All the rich ringing overtones are one of the things I love about having extra bass strings. Almost a reverb like ambience with fresh strings on a good instrument. My Romero Creations Baritone 6 is almost harp like with all the ringing overtones and my 7-string Kremona classical guitar chimes beautifully too. On the other hand, you get much less little chime ambience on the 'ukulele, especially high g strung instruments, since there are no bass string overtones to activate (you still get a wee bit off the open strings).