yes, i know i'm frost specced now, but it happend also when i'm blood specced.
IB supports these instances for tanking
[18:51:20:843] [Instancebuddy]: Currently supported tanking dungeons :
[18:51:20:843] [Instancebuddy]: (This list will update itself automatically)
[18:51:20:843] [Instancebuddy]:
[18:51:20:843] [Instancebuddy]: (Level 15 - 21) Deadmines
[18:51:20:843] [Instancebuddy]: (Level 15 - 21) Ragefire Chasm
[18:51:20:843] [Instancebuddy]: (Level 16 - 26) Shadowfang Keep
[18:51:20:843] [Instancebuddy]: (Level 20 - 30) The Stockade
[18:51:20:843] [Instancebuddy]: (Level 26 - 36) Scarlet Monastery - Graveyard
[18:51:20:843] [Instancebuddy]: (Level 29 - 39) Scarlet Monastery - Library
[18:51:20:843] [Instancebuddy]: (Level 32 - 42) Scarlet Monastery - Armory
[18:51:20:843] [Instancebuddy]: (Level 35 - 45) Scarlet Monastery - Cathedral
[18:51:20:843] [Instancebuddy]: (Level 38 - 48) Scholomance
[18:51:20:843] [Instancebuddy]: (Level 42 - 52) Stratholme - Main Gate
[18:51:20:843] [Instancebuddy]: (Level 46 - 56) Stratholme - Service Entrance
[18:51:20:843] [Instancebuddy]: (Level 57 - 67) Hellfire Ramparts
[18:51:20:843] [Instancebuddy]: (Level 59 - 68) The Blood Furnace
[18:51:20:843] [Instancebuddy]: (Level 62 - 71) Mana Tombs
[18:51:20:843] [Instancebuddy]: (Level 65 - 73) Sethekk Halls
[18:51:20:843] [Instancebuddy]: ---------------------------------