diff --git a/pageserver/src/tenant/timeline/detach_ancestor.rs b/pageserver/src/tenant/timeline/detach_ancestor.rs
index a251677d96..5597ccf498 100644
--- a/pageserver/src/tenant/timeline/detach_ancestor.rs
+++ b/pageserver/src/tenant/timeline/detach_ancestor.rs
@@ -152,6 +152,11 @@ impl SharedState {
         fut: F,
     ) -> T {
         // this needs to wrap the sleeping so that we can quickly let ancestor_detach continue
+        //
+        // FIXME: with the on_gc_task_start this might be unnecessary? no, how would we otherwise
+        // know about gc attempt ending in a failure and sleeping 300s. perhaps the
+        // on_gc_task_start is unnecessary? no, it is needed to know if we ever need to wait for
+        // to start?
         fut.await
     }