I had a similar experience recently. I got two 100 dollar bills from the 70s, as part of payment for a guitar I sold. I tried to deposit them in the ATM and they were rejected. Tried one of them at the local Walmart, and it was rejected. I took them inside my bank and the teller said he'd deposit them into my account. He ran them through two of the bill counters and, instead of putting them in the drawer he set them off to the side, but didn't say anything. The receipt said the funds would be delayed and I asked about it. He said everything was fine, but looked a little nervous.... I was thinking the Secret Service would be flying in on black helicopters anytime
... They were posted to my account a couple days later and all was well. The electronic bill takers don't like old money.