No. Electrum will not have transferred anything. Bitcoin Gold isn't even operational yet. All they did was take a "snapshot" of the blockchain at block# 491407.
One of three things has happened:
1. You wallet file and password have been stolen by a hacker (Malware with keylogger etc)
2. You wallet seed has been compromised (screen grabber, keylogger or you exported it to an unsafe place)
3. The private key(s) for the addresses the coins were stolen from have been compromised.
Did you export your private keys? Did you store your wallet seed in a file on your computer or an online storage service? Did you take a screenshot of your wallet seed or private keys? Did you recently install any pirated software or "free" software from unknown websites/sources?
If you answered "Yes" to any of these questions, the chances of #1, #2 and/or #3 occurring increase significantly. In any case, your coins are gone and your chances of finding out who took them (or getting them back) are pretty much zero
It doesn't matter if your USB was connected or not, if the thief had your wallet+password, seed or private keys... they are free to do whatever they want with your coins.
Even if your malware scan found nothing, I would highly recommend you consider your entire system compromised. I would seriously consider a full system wipe and reinstall of the OS if I was you.
