Are you using 14w25a? If so, you are using an outdated version and the bug will not be fixed in that version. Instead, consider using 14w25b, where the bug is fixed (screenshot attached). However, there is a bug for 14w25b where mining a dark oak log with silk touch gives back a dark oak log with a damage value of 9 (MC-58048) which causes a missing texture. If that is what happened to you, go vote up the earlier issue.
I noticed this started in 14w25a but continued into 14w25b as well. I used iron axe to start to cut down an oak wood tree, only to have the blocks show a pink and black checker icon which says it is an oak wood log. I can't do anything with the log either place it down or turn it into planks.
Are you using 14w25a? If so, you are using an outdated version and the bug will not be fixed in that version. Instead, consider using 14w25b, where the bug is fixed (screenshot attached).
However, there is a bug for 14w25b where mining a dark oak log with silk touch gives back a dark oak log with a damage value of 9 (MC-58048) which causes a missing texture. If that is what happened to you, go vote up the earlier issue.