An issue with 2.5.2+ has been identified and fixed in the latest release and dev updates and the installer on http://skank.i2p/ and http://i2pplus.github.io/.
The issue manifests as a gradual loss of peer connections and floodfills. This was due to the temporary blocking of peers sending unsolicited NetDb store requests. Updating to the latest version (2.5.2-11+) is recommended.