Why Is This Happening? (Contact Sensor Issue)

I have a contact sensor on the electric gate out by our garage. I have 2 notifications configured into the hub in the NOTIFICATION section. Firstly, I have a Pushover notification sent when the gate opens. I have a second notification sent when the gate closes (the gate automatically closes 2 minutes after it has been opened). However, when closing, the two gates don't always close at the same exact speed each time. More often than not, the sensor contact will close when the gates have almost totally closed but then they temporarily separate enough to open the contact for a few seconds.

Here is the sequence of notifications I get from the gate. I get a notification that the gate has been opened, just as designed, a second notification that it has closed, again as designed, but I also get a third that it has opened again. I want to get rid of the erroneous second 'open' notification. To that end, I have applied a limit of only one notification every 5 minutes. In spite of this, I sometimes still get that second 'open' notification. Shouldn't the hub refrain from sending a second 'open' notification until at least 5 minutes has passed?