Yes, normal. The Tesla Model Y will charge the battery when the battery state of charge has fallen by a small percentage, i.e. 5%.
You did not state whether you had set Sentry mode to be On or Off at the location where you parked the Model Y. Sentry mode causes the Tesla Model Y to remain in Standby mode (awake) and not enter Sleep mode. Battery consumption in Standby mode is ~6% to 7% over 24 hours.
With Sentry mode turned off the Tesla Model Y can enter the Sleep mode. The battery consumption in Sleep mode is much less, i.e. ~1% per 7 days; your 5 week vacation may only have resulted in the Tesla Model Y needing to charge a few times. The low voltage battery is automatically maintained using power from the high voltage battery, this drain too will cause the Tesla Model Y to periodically charge the high voltage battery.