@Anderson317
1. For spreads, Tradier treats each option leg separately for their PDT logic and calculation. If you had 2 separate calendar trades that were open and closed on the same day, that would be 2 legs on the first calendar and then 2 legs on the second calendar. So 4 "trades" in one day regardless of how your option legs were setup in spreads. So your guess as to how this happened is right on the mark. This is also what I learned from asking Tradier directly.
2. To remove the PDT status, just email them and ask them to remove it. Simple as that. You can do it once every 90 days. I know because that is what they said and exactly what I did. (I've removed it once so far)
3. To avoid PDT status, don't open and close more than 4 options in a single day. Remember to count each option leg separately in your spreads.
-Note that the actual number of option contracts would not matter. (as least that is my understanding) For example, if you had a calendar position with 42 of the short leg and 42 of the long leg, and you opened and closed it on the same day, that should be 2 day "trades".
For future questions, try asking Tradier directly, they're pretty quick with responses and not bad with their customer service. (Unless you're asking for opinions on steadyoptions. If so, then feel free to ask away. I'm always up for discussion.)
EDIT:
Regarding your message about options expiring today, you should ask Tradier directly as such a message makes no sense at all for today, a Tuesday.