This article explains about the mac address on the ae interface will be changed after the power off / power on of this router. This is the expected behaviour as the MAC address for ae or lacp interface is not physical MAC but logical MAC created by the router. 

Whenever the link flaps for LAG ae interface its MAC address will be changed by default, This change of mac address might break the network connectivity with peer end router/switch that uses mac filter for traffic forwarding or receiving. 

Please find the below juniper document which explains the MAC address allocation for the ae interface explained in detail.

https://supportportal.juniper.net/s/article/Junos-Logic-of-MAC-address-allocation-to-AE-interfaces

Also Every time the interface is flapped it is the default behaviour that logical MAC address will be re-assigned & a new MAC entry will be formed for the same ae interface.