Door lock making weird echo noise

[kmanstream]

i have a 2006 subaru forester. for about 2 weeks now, whenever i unlock or lock my doors from the inside, there is a weird echo (of a similar but fainter locking noise) about 1 second later, which i think might be a delayed relay? the locks are working, but wondering if this is an indication of something about to break? my dealer says they won’t fix it since the locks still work, that this sound is normal, but for 5 years my car never made this noise. i think they are waiting until my warranty expires…thank you.