PDF Document not closed during re-index

When performing a re-index, we encounter a lot of the folloing stacktrace in our server log (I'm guessing probably 1 per pdf document we have).

java.lang.Throwable: Warning: You did not close the PDF Document
at org.pdfbox.cos.COSDocument.finalize(COSDocument.java:384)
at java.lang.ref.Finalizer.invokeFinalizeMethod(Native Method)
at java.lang.ref.Finalizer.runFinalizer(Finalizer.java:83)
at java.lang.ref.Finalizer.access$100(Finalizer.java:14)
at java.lang.ref.Finalizer$FinalizerThread.run(Finalizer.java:160)

I realize this is only a warning and the document is seemingly being closed by the finalize anyways, but we have a lot of attached pdf documents and these clutter the error log making it difficult to see if there are any "real" exceptions occuring.