After not closing the browser I was unable to send notifications after about 45 minutes of inactivity (but still connected). The browser may be "closing" the connection when it loses focus but not sure. Needs to be investigated. I know the UAIDs are being reaped though as I saw this in the log:

[vert.x-eventloop-thread-0] INFO org.jboss.aerogear.simplepush.server.datastore.InMemoryDataStore - Removing [b7a6504b-56ad-4838-b686-656d6b29ca4d] for UserAgent [582be15e-3168-465a-85b7-179b91f862ac]
[vert.x-eventloop-thread-0] INFO org.jboss.aerogear.simplepush.server.datastore.InMemoryDataStore - Removing [1a5d223f-fd86-4372-83d1-5582547723a3] for UserAgent [582be15e-3168-465a-85b7-179b91f862ac]
[vert.x-eventloop-thread-0] INFO org.jboss.aerogear.simplepush.server.datastore.InMemoryDataStore - Removing [28ff9899-d12d-4695-a72d-0742ab43fe56] for UserAgent [582be15e-3168-465a-85b7-179b91f862ac]
Removed all channels for [582be15e-3168-465a-85b7-179b91f862ac] due to inactivity
UserAgentReaper reaping....
[vert.x-eventloop-thread-0] INFO org.jboss.aerogear.simplepush.server.datastore.InMemoryDataStore - Removing [41e976af-cd53-4de4-a6aa-b2632ae55e65] for UserAgent [693b9556-a19b-4acf-a937-a25a638ded35]
[vert.x-eventloop-thread-0] INFO org.jboss.aerogear.simplepush.server.datastore.InMemoryDataStore - Removing [efb5eb37-f0cb-44f2-a84c-0caa5cef8d9c] for UserAgent [693b9556-a19b-4acf-a937-a25a638ded35]
[vert.x-eventloop-thread-0] INFO org.jboss.aerogear.simplepush.server.datastore.InMemoryDataStore - Removing [d413dd38-866a-4074-a9a0-f2e1487db430] for UserAgent [693b9556-a19b-4acf-a937-a25a638ded35]
Removed all channels for [693b9556-a19b-4acf-a937-a25a638ded35] due to inactivity