Can your callers hear themselves talking back to themselves?

[Astrodroid]

I was talking to someone last night and at some point during the call, she said, "Hey I can hear my own voice talking back to me." And when I responded, I realized I could hear myself sort of in stereo. In her case it was distracting because there was a delay. In my case it really wasn't distracting because it was basically same time. It was like hearing myself in stereo. Turning on the speakerphone made it go away, and then when I switched back to normal, it was still gone. But then it came back not long afterwards.

This happening to anyone else?

Possible variable: I was talking at home through my network extender connection. I've been talking through that for a couple weeks though, mostly with the Thunderbolt and only in the past few days with the Incredible 2. This is the first time anyone's said anything. So I don't know if that has anything to do with it.